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What is the benefit of using octal numbers? Isn't it rather confusing?

TAR is the only file format I am aware of which uses base 8 to encode numbers. Octal is neither space-efficient nor human-friendly.

Since TAR is an ancient format, could it be that computers from the 1970 and 1980 were better at dealing with octal numbers? It's the most plausible explanation I can think of.

Octal is directly compatible with binary which basically all computers use and used. Probably easier to program with and encode and decode. Base 2 (binary) to base 8 (octal) is easier for programmers than base 10 because a power of 2 (2 to power 3) is 8. X E.

Then why wasn't hexadecimal used? Hexadecimal (base 16) is also a power of two.

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Just an old format, tape archive (tar) may just be old and used to be used for things with fewer bits. Not an expert but I know that tar stands for tape archive which is old. X E.

The advantage of octal over hexadecimal is that you only need numerals. It was widely used in the early days of computing and still lingers on in Linux — see the man entry for chmod, for example.

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Dunno. Hewlett-Packard designed their "HP3000" family of minicomputers on a reverse-polish stack architecture, just as they did their pocket calculators. And, they also consistently used octal notation. Never knew why, exactly. But you quickly got used to it.

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Seriously??? Don't you claim to be an 'experienced programmer' who knows 8 of the top ten languages??? How is it 'easier' for programmers to work with, when things are written in a high-level language (like C) and compiled down?? This is another case of a utility being written a long time ago on vastly different hardware; has more to do with the PDP era machines and the size of their respective bit-blocks. Zero to do with "it's easier to divide 8 by 2". You do realize that computers do math pretty well, right???

And do you mind explaining how octal is 'directly compatible with binary'???
...which is pretty much what DavidMcCann said, regarding older hardware. And if you think tape isn't used any longer...you are SERIOUSLY mistaken (again).

And *STOP* with the 'XE' garbage.

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Simple search with duckduckgo (no inference engine needed):

From wiki:

Octal became widely used in computing when systems such as the UNIVAC 1050, PDP-8, ICL 1900 and IBM mainframes employed 6-bit, 12-bit, 24-bit or 36-bit words. Octal was an ideal abbreviation of binary for these machines because their word size is divisible by three (each octal digit represents three binary digits). So two, four, eight or twelve digits could concisely display an entire machine word. It also cut costs by allowing Nixie tubes, seven-segment displays, and calculators to be used for the operator consoles, where binary displays were too complex to use, decimal displays needed complex hardware to convert radices, and hexadecimal displays needed to display more numerals.

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Looking over at my PDP 11/70 front panel, all the switches are in 3 digit groups (octal). Just the way it was. Octal is no harder to learn than binary, base 10, base 16 (hex).... That said this was a 16 bit Word machine (unlike earlier 12 bit PDP-8 for example), but had 22 bit memory management. The memory management could translate 18bit Unibus map addresses to 22 bits. Seems a bit complicated looking back .



Hope that helps

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Off-topic but if you have an 11/70 front panel laying around, you might find the PiDP-11 project/kit interesting. Someone with 11/70 maintenance prints and some hardware skills ought to be able to bring a real 11/70 console back to a functional life. (I've got an old RPi 2 looking for a purpose in life and it'd be fun to dive into RSX-11M-PLUS again.)

There was a time when people programmers worked with octal so much that they found themselves balancing their checkbooks in octal. No doubt it's a holdover from those days.

I should have said my 1/3 size PDP 11/70 front panel powered by a RPI-5 . Great kit. Looking at the new PiDP-10 as another project .